package Ajax;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class CertifyImage extends HttpServlet {

	/**
	 * 
	 */
	private static final long serialVersionUID = 8837476516287739088L;

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws IOException, ServletException {
		int width = 60;
		int height = 20;
		// 创建具有可访问图像数据缓冲区的Image
		BufferedImage buffImg = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_RGB);
		Graphics2D g = buffImg.createGraphics();
		
		// 创建一个随机数生成器
		Random random = new Random();
		
		g.setColor(Color.WHITE);
		g.fillRect(0, 0, width, height);
		
		// 创建字体，字体的大小应该根据图片的高度来定
		Font font = new Font("Times New Roman", Font.PLAIN, 18);
		// 设置字体
		g.setFont(font);
		
		// 画边框
		g.setColor(Color.BLACK);
		g.drawRect(0, 0, width - 1, height - 1);
		
		// 随机产生160条干扰线
		g.setColor(Color.LIGHT_GRAY);
		for (int i = 0; i < 160; i++) {
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			int x1 = random.nextInt(12);
			int y1 = random.nextInt(12);
			g.drawLine(x, y, x + x1, y + y1);
		}
		
		// randomCode 用于保存随机产生的验证码
		StringBuffer randomCode = new StringBuffer();
		int red = 0, green = 0, blue = 0;
		
		// 随机产生4位数字的验证码
		for (int i = 0; i < 4; i++) {
			// 得到随机产生的验证码数字
			String strRand = String.valueOf(random.nextInt(10));
		
			// 产生随机的颜色分量来构造颜色值
			red = random.nextInt(110);
			green = random.nextInt(50);
			blue = random.nextInt(50);
		
			// 用随机产生的颜色将验证码绘制到图像中
			g.setColor(new Color(red, green, blue));
			g.drawString(strRand, 13 * i + 6, 16);
		
			randomCode.append(strRand);
		}

		// 将四位数字的验证码保存到session中
		HttpSession session = request.getSession();
		session.setAttribute("randomCode", randomCode.toString());

		// 禁止图像缓存
		response.setHeader("Pragma", "no-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);

		response.setContentType("image/jpeg");
		// 将图像输出到servlet输出流中
		ServletOutputStream sos = response.getOutputStream();
		ImageIO.write(buffImg, "jpeg", sos);
		sos.close();
	}
}
